Current commercial catalysts for hydrogenolysis of fatty acid esters utilize CuCr tablets. These catalysts are activated with hydrogen to reduce the CuO to form what is commonly believed to be the active site. Without being bound by theory, it is believed the active site involves Cuo. The feed for producing fatty alcohols may contain impurities, such as, but not limited to, sulfur or free fatty acids (FFAs). Sulfur can poison Cuo active sites in the catalyst, thereby deactivating the catalyst. FFAs may compete for adsorption sites where ester hydrogenolysis takes place, thereby significantly inhibiting the rate of ester hydrogenolysis (a reversible deactivation). FFAs may also accelerate the Cuo crystallite growth thereby causing activity loss (a permanent deactivation). The main causes of catalyst deactivation are: copper crystallite growth, sulfur, and coke deposition.